Stopping power is mostly a made up term. If its not supported by physics don't believe it. Knock down power is another one. plain old lead bullets and FMJ bullets have killed more people then designer hps ever will. People will tell you that you need a gun and ammo that will hold x group at 25 yards etc etc. Its all bs. Shot placement is something you can predict when you control the environment. It is not something you can predict in combat or a self defense situation. Putting a deep penetrating bullet on your target is all that matters. The bigger hole you can put through and through the better chance you have of stopping the threat.